1. Field of the Invention
Catechol amine solutions, particularly epinephrine and modifications thereof, have wide application for medicinal purposes. One application for epinephrine is the use in the treatment in ophthalmological diseases, such as glaucoma. Because of the extreme sensitivity of the eye to irritation by relatively mild aqueous acid or base, as well as numerous chemical irritants, any physiologically useful solution should be substantially non-irritating to the eye.
Epinephrine is a catecholhydroxyalkyl amine. The catechol compounds are particularly sensitive to oxidation to o-quinones, which can react further to form highly colored compounds. In fact, epinephrine can react to form adrenochrome, a highly colored indole derivative.
The modification or degradation of the catechol amines is undesirable for a number of reasons. Modification of the catechol amine results in loss of titer of the active ingredient, formation of compounds which may have undesirable physiological effects, and the appearance of a dark color, which makes the solution offensive and unmarketable.
The manner of use of a solution for eye treatment maintains an aerobic or oxidative environment. Normally, an eye dropper is used and treatment is carried out on a periodic basis. Therefore, for each treatment, air is in contact with the solution and the oxygen in the solution replenished. Even in a brown bottle, the solution will be repeatedly exposed to light, which may initiate reactions which may then proceed in the dark.
2. Description of the Prior Art
U.S. Pat. No. 3,149,035 employs bisulphite and boric acid in combination with catechol amines to enhance stability of the catechol amines. French Pat. No. 4.549 M discloses improved stability of therapeutic amine solutions containing polyvinylpyrrolidone, by insuring the removal of monomer and any aldehydes which may be adventitiously present in the commercially available polyvinylpyrrolidone.